diff --git a/runtime/ftplugin/forth.vim b/runtime/ftplugin/forth.vim
new file mode 100644
index 0000000..5343784
--- /dev/null
+++ b/runtime/ftplugin/forth.vim
@@ -0,0 +1,71 @@
+" Vim filetype plugin
+" Language:	Forth
+" Maintainer:	Johan Kotlinski <kotlinski@gmail.com>
+" Last Change:	2023 Aug 08
+" URL:		https://github.com/jkotlinski/forth.vim
+
+if exists("b:did_ftplugin")
+  finish
+endif
+let b:did_ftplugin = 1
+
+let s:cpo_save = &cpo
+set cpo&vim
+
+setlocal commentstring=\\\ %s
+setlocal comments=s:(,mb:\ ,e:),b:\\
+setlocal iskeyword=33-126,128-255
+
+let s:include_patterns =<< trim EOL
+
+  \<\%(INCLUDE\|REQUIRE\)\>\s\+\zs\k\+\ze
+  \<S"\s\+\zs[^"]*\ze"\s\+\%(INCLUDED\|REQUIRED\)\>
+EOL
+let &l:include = $'\c{ s:include_patterns[1:]->join('\|') }'
+
+let s:define_patterns =<< trim EOL
+  :
+  [2F]\=CONSTANT
+  [2F]\=VALUE
+  [2F]\=VARIABLE
+  BEGIN-STRUCTURE
+  BUFFER:
+  CODE
+  CREATE
+  MARKER
+  SYNONYM
+EOL
+let &l:define = $'\c\<\%({ s:define_patterns->join('\|') }\)'
+
+" assume consistent intra-project file extensions
+let &l:suffixesadd = "." .. expand("%:e")
+
+let b:undo_ftplugin = "setl cms< com< def< inc< isk< sua<"
+
+if exists("loaded_matchit") && !exists("b:match_words")
+  let s:matchit_patterns =<< trim EOL
+
+    \<\:\%(NONAME\)\=\>:\<EXIT\>:\<;\>
+    \<IF\>:\<ELSE\>:\<THEN\>
+    \<\[IF]\>:\<\[ELSE]\>:\<\[THEN]\>
+    \<?\=DO\>:\<LEAVE\>:\<+\=LOOP\>
+    \<CASE\>:\<ENDCASE\>
+    \<OF\>:\<ENDOF\>
+    \<BEGIN\>:\<WHILE\>:\<\%(AGAIN\|REPEAT\|UNTIL\)\>
+    \<CODE\>:\<END-CODE\>
+    \<BEGIN-STRUCTURE\>:\<END-STRUCTURE\>
+  EOL
+  let b:match_ignorecase = 1
+  let b:match_words = s:matchit_patterns[1:]->join(',')
+  let b:undo_ftplugin ..= "| unlet! b:match_ignorecase b:match_words"
+endif
+
+if (has("gui_win32") || has("gui_gtk")) && !exists("b:browsefilter")
+  let b:browsefilter = "Forth Source Files (*.f *.fs *.ft *.fth *.4th)\t*.f;*.fs;*.ft;*.fth;*.4th\n" ..
+	\	       "All Files (*.*)\t*.*\n"
+  let b:undo_ftplugin ..= " | unlet! b:browsefilter"
+endif
+
+let &cpo = s:cpo_save
+unlet s:cpo_save
+unlet s:define_patterns s:include_patterns s:matchit_patterns
diff --git a/runtime/syntax/forth.vim b/runtime/syntax/forth.vim
index fe98634..252116a 100644
--- a/runtime/syntax/forth.vim
+++ b/runtime/syntax/forth.vim
@@ -1,10 +1,20 @@
 " Vim syntax file
-" Language:    FORTH
-" Current Maintainer:  Johan Kotlinski <kotlinski@gmail.com>
-" Previous Maintainer:  Christian V. J. Br�ssow <cvjb@cvjb.de>
-" Last Change: 2023-01-12
-" Filenames:   *.fs,*.ft
-" URL:	       https://github.com/jkotlinski/forth.vim
+" Language:		Forth
+" Maintainer:		Johan Kotlinski <kotlinski@gmail.com>
+" Previous Maintainer:	Christian V. J. Brüssow <cvjb@cvjb.de>
+" Last Change:		2023 Aug 13
+" Filenames:		*.f,*.fs,*.ft,*.fth,*.4th
+" URL:			https://github.com/jkotlinski/forth.vim
+
+" Supports the Forth-2012 Standard.
+"
+" Removed words from the earlier Forth-79, Forth-83 and Forth-94 standards are
+" also included.
+"
+" These have been organised according to the version in which they were
+" initially included and the version in which they were removed (obsolescent
+" status is ignored).  Words with "experimental" or "uncontrolled" status are
+" not included unless they were later standardised.
 
 " quit when a syntax file was already loaded
 if exists("b:current_syntax")
@@ -15,19 +25,15 @@
 set cpo&vim
 
 " Synchronization method
-syn sync ccomment
-syn sync maxlines=200
+exe "syn sync minlines=" .. get(g:, "forth_minlines", 50)
 
-" I use gforth, so I set this to case ignore
 syn case ignore
 
-" Some special, non-FORTH keywords
-syn keyword forthTodo contained TODO FIXME XXX
-
 " Characters allowed in keywords
 " I don't know if 128-255 are allowed in ANS-FORTH
-setlocal iskeyword=!,@,33-35,%,$,38-64,A-Z,91-96,a-z,123-126,128-255
+syn iskeyword 33-126,128-255
 
+" Space errors {{{1
 " when wanted, highlight trailing white space
 if exists("forth_space_errors")
     if !exists("forth_no_trail_space_error")
@@ -38,188 +44,369 @@
     endif
 endif
 
-" Keywords
+" Core words {{{1
 
-" basic mathematical and logical operators
-syn keyword forthOperators + - * / MOD /MOD NEGATE ABS MIN MAX
-syn keyword forthOperators AND OR XOR NOT LSHIFT RSHIFT INVERT 2* 2/ 1+
-syn keyword forthOperators 1- 2+ 2- 8* UNDER+
-syn keyword forthOperators M+ */ */MOD M* UM* M*/ UM/MOD FM/MOD SM/REM
-syn keyword forthOperators D+ D- DNEGATE DABS DMIN DMAX D2* D2/
-syn keyword forthOperators F+ F- F* F/ FNEGATE FABS FMAX FMIN FLOOR FROUND
-syn keyword forthOperators F** FSQRT FEXP FEXPM1 FLN FLNP1 FLOG FALOG FSIN
-syn keyword forthOperators FCOS FSINCOS FTAN FASIN FACOS FATAN FATAN2 FSINH
-syn keyword forthOperators FCOSH FTANH FASINH FACOSH FATANH F2* F2/ 1/F
-syn keyword forthOperators F~REL F~ABS F~
-syn keyword forthOperators 0< 0<= 0<> 0= 0> 0>= < <= <> = > >= U< U<=
-syn keyword forthOperators U> U>= D0< D0<= D0<> D0= D0> D0>= D< D<= D<>
-syn keyword forthOperators D= D> D>= DU< DU<= DU> DU>= WITHIN ?NEGATE
-syn keyword forthOperators ?DNEGATE TRUE FALSE
+" basic mathematical and logical operators {{{2
+syn keyword forthOperators * */ */MOD + - / /MOD 0< 0= 1+ 1- 2* 2/ < = > ABS
+syn keyword forthOperators AND FM/MOD INVERT LSHIFT M* MAX MIN MOD NEGATE OR
+syn keyword forthOperators RSHIFT SM/REM U< UM* UM/MOD XOR
+  " extension words
+syn keyword forthOperators 0<> 0> <> U> WITHIN
+  " Forth-79
+syn keyword forthOperators U* U/ U/MOD
+  " Forth-79, Forth-83
+syn keyword forthOperators NOT
+  " Forth-83
+syn keyword forthOperators 2+ 2-
 
-" various words that take an input and do something with it
-syn keyword forthFunction . U. .R U.R
+" non-standard basic mathematical and logical operators
+syn keyword forthOperators 0<= 0>= 8* <= >= ?DNEGATE ?NEGATE U<= U>= UNDER+
 
-" stack manipulations
-syn keyword forthStack DROP NIP DUP OVER TUCK SWAP ROT -ROT ?DUP PICK ROLL
-syn keyword forthStack 2DROP 2NIP 2DUP 2OVER 2TUCK 2SWAP 2ROT 2-ROT
-syn keyword forthStack 3DUP 4DUP 5DUP 3DROP 4DROP 5DROP 8DROP 4SWAP 4ROT
-syn keyword forthStack 4-ROT 4TUCK 8SWAP 8DUP
-syn keyword forthRStack >R R> R@ RDROP 2>R 2R> 2R@ 2RDROP
-syn keyword forthRstack 4>R 4R> 4R@ 4RDROP
-syn keyword forthFStack FDROP FNIP FDUP FOVER FTUCK FSWAP FROT
+" various words that take an input and do something with it {{{2
+syn keyword forthFunction . U.
+  " extension words
+syn keyword forthFunction .R U.R
 
-" stack pointer manipulations
-syn keyword forthSP SP@ SP! FP@ FP! RP@ RP! LP@ LP! DEPTH
+" stack manipulations {{{2
+syn keyword forthStack 2DROP 2DUP 2OVER 2SWAP >R ?DUP DROP DUP OVER R> R@ ROT
+syn keyword forthStack SWAP
+  " extension words
+syn keyword forthStack  NIP PICK ROLL TUCK
+syn keyword forthRStack 2>R 2R> 2R@
 
-" address operations
-syn keyword forthMemory @ ! +! C@ C! 2@ 2! F@ F! SF@ SF! DF@ DF!
-syn keyword forthAdrArith CHARS CHAR+ CELLS CELL+ CELL ALIGN ALIGNED FLOATS
-syn keyword forthAdrArith FLOAT+ FLOAT FALIGN FALIGNED SFLOATS SFLOAT+
-syn keyword forthAdrArith SFALIGN SFALIGNED DFLOATS DFLOAT+ DFALIGN DFALIGNED
-syn keyword forthAdrArith MAXALIGN MAXALIGNED CFALIGN CFALIGNED
-syn keyword forthAdrArith ADDRESS-UNIT-BITS ALLOT ALLOCATE HERE
-syn keyword forthMemBlks MOVE ERASE CMOVE CMOVE> FILL BLANK UNUSED
+" non-standard stack manipulations
+syn keyword forthStack  -ROT 3DROP 3DUP 4-ROT 4DROP 4DUP 4ROT 4SWAP 4TUCK
+syn keyword forthStack  5DROP 5DUP 8DROP 8DUP 8SWAP
+syn keyword forthRStack 4>R 4R> 4R@ 4RDROP RDROP
 
-" conditionals
-syn keyword forthCond IF ELSE ENDIF THEN CASE OF ENDOF ENDCASE ?DUP-IF
-syn keyword forthCond ?DUP-0=-IF AHEAD CS-PICK CS-ROLL CATCH THROW WITHIN
+" stack pointer manipulations {{{2
+syn keyword forthSP DEPTH
 
-" iterations
-syn keyword forthLoop BEGIN WHILE REPEAT UNTIL AGAIN
-syn keyword forthLoop ?DO LOOP I J K +DO U+DO -DO U-DO DO +LOOP -LOOP
-syn keyword forthLoop UNLOOP LEAVE ?LEAVE EXIT DONE FOR NEXT RECURSE
+" non-standard stack pointer manipulations
+syn keyword forthSP FP!  FP@ LP!  LP@ RP!  RP@ SP!  SP@
 
-" new words
-syn match forthClassDef '\<:class\s*[^ \t]\+\>'
-syn match forthObjectDef '\<:object\s*[^ \t]\+\>'
-syn match forthColonDef '\<:m\?\s*[^ \t]\+\>'
-syn keyword forthEndOfColonDef ; ;M ;m
-syn keyword forthEndOfClassDef ;class
-syn keyword forthEndOfObjectDef ;object
-syn keyword forthDefine CONSTANT 2CONSTANT FCONSTANT VARIABLE 2VARIABLE
-syn keyword forthDefine FVARIABLE CREATE USER VALUE TO DEFER IS <BUILDS DOES> IMMEDIATE
-syn keyword forthDefine COMPILE-ONLY COMPILE RESTRICT INTERPRET POSTPONE EXECUTE
-syn keyword forthDefine LITERAL CREATE-INTERPRET/COMPILE INTERPRETATION>
-syn keyword forthDefine <INTERPRETATION COMPILATION> <COMPILATION ] LASTXT
-syn keyword forthDefine COMP' POSTPONE, FIND-NAME NAME>INT NAME?INT NAME>COMP
-syn keyword forthDefine NAME>STRING STATE C; CVARIABLE BUFFER: MARKER
-syn keyword forthDefine , 2, F, C, COMPILE,
-syn match forthDefine "\[DEFINED]"
-syn match forthDefine "\[UNDEFINED]"
-syn match forthDefine "\[IF]"
-syn match forthDefine "\[IFDEF]"
-syn match forthDefine "\[IFUNDEF]"
-syn match forthDefine "\[THEN]"
-syn match forthDefine "\[ENDIF]"
-syn match forthDefine "\[ELSE]"
-syn match forthDefine "\[?DO]"
-syn match forthDefine "\[DO]"
-syn match forthDefine "\[LOOP]"
-syn match forthDefine "\[+LOOP]"
-syn match forthDefine "\[NEXT]"
-syn match forthDefine "\[BEGIN]"
-syn match forthDefine "\[UNTIL]"
-syn match forthDefine "\[AGAIN]"
-syn match forthDefine "\[WHILE]"
-syn match forthDefine "\[REPEAT]"
-syn match forthDefine "\[COMP']"
-syn match forthDefine "'"
-syn match forthDefine '\<\[\>'
-syn match forthDefine "\[']"
-syn match forthDefine '\[COMPILE]'
-syn match forthDefine '\[CHAR]'
+" address operations {{{2
+syn keyword forthMemory !  +!  2!  2@ @ C!  C@
+syn keyword forthAdrArith ALIGN ALIGNED ALLOT CELL+ CELLS CHAR+ CHARS
+syn keyword forthMemBlks  FILL MOVE
+  " extension words
+syn keyword forthMemBlks  ERASE UNUSED
 
-" debugging
-syn keyword forthDebug PRINTDEBUGDATA PRINTDEBUGLINE
-syn match forthDebug "\<\~\~\>"
+" non-standard address operations
+syn keyword forthAdrArith ADDRESS-UNIT-BITS CELL CFALIGN CFALIGNED FLOAT
+syn keyword forthAdrArith MAXALIGN MAXALIGNED
 
-" Assembler
-syn keyword forthAssembler ASSEMBLER CODE END-CODE ;CODE FLUSH-ICACHE C,
+" conditionals {{{2
+syn keyword forthCond ELSE IF THEN
+  " extension words
+syn keyword forthCond CASE ENDCASE ENDOF OF
 
-" basic character operations
-syn keyword forthCharOps (.) CHAR EXPECT FIND WORD TYPE -TRAILING EMIT KEY
-syn keyword forthCharOps KEY? TIB CR BL COUNT SPACE SPACES
-" recognize 'char (' or '[char] (' correctly, so it doesn't
+" non-standard conditionals
+syn keyword forthCond ?DUP-0=-IF ?DUP-IF ENDIF
+
+" iterations {{{2
+syn keyword forthLoop +LOOP BEGIN DO EXIT I J LEAVE LOOP RECURSE REPEAT UNLOOP
+syn keyword forthLoop UNTIL WHILE
+  " extension words
+syn keyword forthLoop ?DO AGAIN
+
+" non-standard iterations
+syn keyword forthLoop +DO -DO -LOOP ?LEAVE DONE FOR K NEXT U+DO U-DO
+
+" new words {{{2
+syn match   forthColonDef      "\<:\s*[^ \t]\+\>"
+syn keyword forthEndOfColonDef ;
+syn keyword forthDefine ' , C, CONSTANT CREATE DOES> EXECUTE IMMEDIATE LITERAL
+syn keyword forthDefine POSTPONE STATE VARIABLE ]
+syn match   forthDefine "\<\[']\>"
+syn match   forthDefine "\<\[\>"
+  " extension words
+syn keyword forthColonDef :NONAME
+syn keyword forthDefine   BUFFER: COMPILE, DEFER IS MARKER TO VALUE
+syn match   forthDefine   "\<\[COMPILE]\>"
+  " Forth-79, Forth-83
+syn keyword forthDefine COMPILE
+
+" non-standard new words
+syn match   forthClassDef       "\<:CLASS\s*[^ \t]\+\>"
+syn keyword forthEndOfClassDef  ;CLASS
+syn match   forthObjectDef      "\<:OBJECT\s*[^ \t]\+\>"
+syn keyword forthEndOfObjectDef ;OBJECT
+syn match   forthColonDef       "\<:M\s*[^ \t]\+\>"
+syn keyword forthEndOfColonDef  ;M
+syn keyword forthDefine 2, <BUILDS <COMPILATION <INTERPRETATION C; COMP'
+syn keyword forthDefine COMPILATION> COMPILE-ONLY CREATE-INTERPRET/COMPILE
+syn keyword forthDefine CVARIABLE F, FIND-NAME INTERPRET INTERPRETATION>
+syn keyword forthDefine LASTXT NAME>COMP NAME>INT NAME?INT POSTPONE, RESTRICT
+syn keyword forthDefine USER
+syn match   forthDefine "\<\[COMP']\>"
+
+" basic character operations {{{2
+syn keyword forthCharOps BL COUNT CR EMIT FIND KEY SPACE SPACES TYPE WORD
+" recognize 'char (' or '[CHAR] (' correctly, so it doesn't
 " highlight everything after the paren as a comment till a closing ')'
-syn match forthCharOps '\<char\s\S\s'
-syn match forthCharOps '\<\[char\]\s\S\s'
-syn region forthCharOps start=+."\s+ skip=+\\"+ end=+"+
+syn match forthCharOps '\<CHAR\s\S\s'
+syn match forthCharOps '\<\[CHAR]\s\S\s'
+  " Forth-83, Forth-94
+syn keyword forthCharOps EXPECT #TIB TIB
 
-" char-number conversion
-syn keyword forthConversion <<# <# # #> #>> #S (NUMBER) (NUMBER?) CONVERT D>F
-syn keyword forthConversion D>S DIGIT DPL F>D HLD HOLD NUMBER S>D SIGN >NUMBER
-syn keyword forthConversion F>S S>F HOLDS
+" non-standard basic character operations
+syn keyword forthCharOps (.)
 
-" interpreter, wordbook, compiler
-syn keyword forthForth (LOCAL) BYE COLD ABORT >BODY >NEXT >LINK CFA >VIEW HERE
-syn keyword forthForth PAD WORDS VIEW VIEW> N>LINK NAME> LINK> L>NAME FORGET
-syn keyword forthForth BODY> ASSERT( ASSERT0( ASSERT1( ASSERT2( ASSERT3( )
-syn keyword forthForth >IN ACCEPT ENVIRONMENT? EVALUATE QUIT SOURCE ACTION-OF
-syn keyword forthForth DEFER! DEFER@ PARSE PARSE-NAME REFILL RESTORE-INPUT
-syn keyword forthForth SAVE-INPUT SOURCE-ID
-syn region forthForth start=+ABORT"\s+ skip=+\\"+ end=+"+
+" char-number conversion {{{2
+syn keyword forthConversion # #> #S <# >NUMBER HOLD S>D SIGN
+  " extension words
+syn keyword forthConversion HOLDS
+  " Forth-79, Forth-83, Forth-93
+syn keyword forthConversion CONVERT
 
-" vocabularies
-syn keyword forthVocs ONLY FORTH ALSO ROOT SEAL VOCS ORDER CONTEXT #VOCS
-syn keyword forthVocs VOCABULARY DEFINITIONS
+" non-standard char-number conversion
+syn keyword forthConversion #>> (NUMBER) (NUMBER?) <<# DIGIT DPL HLD NUMBER
 
-" File keywords
-syn keyword forthFileMode R/O R/W W/O BIN
-syn keyword forthFileWords OPEN-FILE CREATE-FILE CLOSE-FILE DELETE-FILE
-syn keyword forthFileWords RENAME-FILE READ-FILE READ-LINE KEY-FILE
-syn keyword forthFileWords KEY?-FILE WRITE-FILE WRITE-LINE EMIT-FILE
-syn keyword forthFileWords FLUSH-FILE FILE-STATUS FILE-POSITION
-syn keyword forthFileWords REPOSITION-FILE FILE-SIZE RESIZE-FILE
-syn keyword forthFileWords SLURP-FILE SLURP-FID STDIN STDOUT STDERR
-syn keyword forthFileWords INCLUDE-FILE INCLUDED REQUIRED
-syn keyword forthBlocks OPEN-BLOCKS USE LOAD --> BLOCK-OFFSET
-syn keyword forthBlocks GET-BLOCK-FID BLOCK-POSITION LIST SCR BLOCK
-syn keyword forthBlocks BUFER EMPTY-BUFFERS EMPTY-BUFFER UPDATE UPDATED?
-syn keyword forthBlocks SAVE-BUFFERS SAVE-BUFFER FLUSH THRU +LOAD +THRU
-syn keyword forthBlocks BLOCK-INCLUDED BLK
+" interpreter, wordbook, compiler {{{2
+syn keyword forthForth >BODY >IN ACCEPT ENVIRONMENT?  EVALUATE HERE QUIT SOURCE
+  " extension words
+syn keyword forthForth ACTION-OF DEFER!  DEFER@ PAD PARSE PARSE-NAME REFILL
+syn keyword forthForth RESTORE-INPUT SAVE-INPUT SOURCE-ID
+  " Forth-79
+syn keyword forthForth 79-STANDARD
+  " Forth-83
+syn keyword forthForth <MARK <RESOLVE >MARK >RESOLVE ?BRANCH BRANCH FORTH-83
+  " Forth-79, Forth-83, Forth-94
+syn keyword forthForth QUERY
+  " Forth-83, Forth-94
+syn keyword forthForth SPAN
 
-" numbers
-syn keyword forthMath DECIMAL HEX BASE
-syn match forthInteger '\<-\=[0-9]\+.\=\>'
-syn match forthInteger '\<&-\=[0-9]\+.\=\>'
-syn match forthInteger '\<#-\=[0-9]\+.\=\>'
-" recognize hex and binary numbers, the '$' and '%' notation is for gforth
-syn match forthInteger '\<\$\x*\x\+\>' " *1* --- don't mess
-syn match forthInteger '\<\x*\d\x*\>'  " *2* --- this order!
-syn match forthInteger '\<%[0-1]*[0-1]\+\>'
-syn match forthFloat '\<-\=\d*[.]\=\d\+[DdEe]\d\+\>'
-syn match forthFloat '\<-\=\d*[.]\=\d\+[DdEe][-+]\d\+\>'
+" non-standard interpreter, wordbook, compiler
+syn keyword forthForth ) >LINK >NEXT >VIEW ASSERT( ASSERT0( ASSERT1( ASSERT2(
+syn keyword forthForth ASSERT3( BODY> CFA COLD L>NAME LINK> N>LINK NAME> VIEW
+syn keyword forthForth VIEW>
 
-" XXX If you find this overkill you can remove it. this has to come after the
-" highlighting for numbers otherwise it has no effect.
-syn region forthComment start='0 \[if\]' end='\[endif\]' end='\[then\]' contains=forthTodo
+" booleans {{{2
+  " extension words
+syn match forthBoolean "\<\%(TRUE\|FALSE\)\>"
 
-" Strings
-syn region forthString start=+\.*\"+ end=+"+ end=+$+ contains=@Spell
-" XXX
-syn region forthString start=+s\"+ end=+"+ end=+$+ contains=@Spell
-syn region forthString start=+s\\\"+ end=+"+ end=+$+ contains=@Spell
-syn region forthString start=+c\"+ end=+"+ end=+$+ contains=@Spell
+" numbers {{{2
+syn keyword forthMath  BASE DECIMAL
+  " extension words
+syn keyword forthMath  HEX
+syn match forthInteger '\<-\=\d\+\.\=\>'
+syn match forthInteger '\<#-\=\d\+\.\=\>'
+syn match forthInteger '\<\$-\=\x\+\.\=\>'
+syn match forthInteger '\<%-\=[01]\+\.\=\>'
 
-" Comments
-syn match forthComment '\\\%(\s.*\)\=$' contains=@Spell,forthTodo,forthSpaceError
-syn region forthComment start='\\S\s' end='.*' contains=@Spell,forthTodo,forthSpaceError
-syn match forthComment '\.(\s[^)]*)' contains=@Spell,forthTodo,forthSpaceError
-syn region forthComment start='\(^\|\s\)\zs(\s' skip='\\)' end=')' contains=@Spell,forthTodo,forthSpaceError
-syn region forthComment start='/\*' end='\*/' contains=@Spell,forthTodo,forthSpaceError
+" characters {{{2
+syn match forthCharacter "'\k'"
 
-" Include files
-syn match forthInclude '^INCLUDE\s\+\k\+'
-syn match forthInclude '^REQUIRE\s\+\k\+'
+" strings {{{2
+
+" Words that end with " are assumed to start string parsing.
+" This includes standard words: S" ."
+syn region forthString matchgroup=forthString start=+\<\S\+"\s+ end=+"+ end=+$+ contains=@Spell
+  " extension words
+syn region forthString matchgroup=forthString start=+\<C"\s+ end=+"+ end=+$+ contains=@Spell
+" Matches S\"
+syn region forthString matchgroup=forthString start=+\<S\\"\s+ end=+"+ end=+$+ contains=@Spell,forthEscape
+
+syn match forthEscape +\C\\[abeflmnqrtvz"\\]+ contained
+syn match forthEscape "\C\\x\x\x" contained
+
+" comments {{{2
+
+syn keyword forthTodo contained TODO FIXME XXX
+
+" Some special, non-FORTH keywords
+syn match forthTodo contained "\<\%(TODO\|FIXME\|XXX\)\%(\>\|:\@=\)"
+
+" XXX If you find this overkill you can remove it. This has to come after the
+" highlighting for numbers and booleans otherwise it has no effect.
+syn region forthComment start='\<\%(0\|FALSE\)\s\+\[IF]' end='\<\[ENDIF]' end='\<\[THEN]' contains=forthTodo
+
+if get(g:, "forth_no_comment_fold", 0)
+    syn region forthComment start='\<(\>' end=')' contains=@Spell,forthTodo,forthSpaceError
+      " extension words
+    syn match  forthComment '\<\\\>.*$' contains=@Spell,forthTodo,forthSpaceError
+else
+    syn region forthComment start='\<(\>' end=')' contains=@Spell,forthTodo,forthSpaceError fold
+      " extension words
+    syn match  forthComment '\<\\\>.*$' contains=@Spell,forthTodo,forthSpaceError
+    syn region forthMultilineComment start="^\s*\\\>" end="\n\%(\s*\\\>\)\@!" contains=forthComment transparent fold
+endif
+
+  " extension words
+syn region forthComment start='\<\.(\>' end=')' end='$' contains=@Spell,forthTodo,forthSpaceError
+
+" ABORT {{{2
+syn keyword forthForth ABORT
+syn region forthForth start=+\<ABORT"\s+ end=+"\>+ end=+$+
+
+" The optional Block word set {{{1
+" Handled as Core words - REFILL
+syn keyword forthBlocks BLK BLOCK BUFFER FLUSH LOAD SAVE-BUFFERS UPDATE
+  " extension words
+syn keyword forthBlocks EMPTY-BUFFERS LIST SCR THRU
+
+" Non-standard Block words
+syn keyword forthBlocks +LOAD +THRU --> BLOCK-INCLUDED BLOCK-OFFSET
+syn keyword forthBlocks BLOCK-POSITION EMPTY-BUFFER GET-BLOCK-FID OPEN-BLOCKS
+syn keyword forthBlocks SAVE-BUFFER UPDATED? USE
+
+" The optional Double-Number word set {{{1
+syn keyword forthConversion D>S
+syn keyword forthDefine     2CONSTANT 2LITERAL 2VARIABLE
+syn keyword forthFunction   D. D.R
+syn keyword forthOperators  D+ D- D0= D2* D2/ D= DABS DMAX DMIN DNEGATE
+syn keyword forthOperators  D0< D< M+ M*/
+  " extension words
+syn keyword forthDefine    2VALUE
+syn keyword forthOperators DU<
+syn keyword forthStack     2ROT
+
+" Non-standard Double-Number words
+syn keyword forthOperators D0<= D0<> D0> D0>= D<= D<> D> D>= DU<= DU> DU>=
+syn keyword forthStack     2-ROT 2NIP 2RDROP 2TUCK
+
+" The optional Exception word set {{{1
+" Handled as Core words - ABORT ABORT"
+syn keyword forthCond CATCH THROW
+
+" The optional Facility word set {{{1
+syn keyword forthCharOps AT-XY KEY?  PAGE
+  " extension words
+syn keyword forthCharOps EKEY EKEY>CHAR EKEY>FKEY EKEY?  EMIT?  K-ALT-MASK
+syn keyword forthCharOps K-CTRL-MASK K-DELETE K-DOWN K-END K-F1 K-F10 K-F11
+syn keyword forthCharOps K-F12 K-F2 K-F3 K-F4 K-F5 K-F6 K-F7 K-F8 K-F9 K-HOME
+syn keyword forthCharOps K-INSERT K-LEFT K-NEXT K-PRIOR K-RIGHT K-SHIFT-MASK
+syn keyword forthCharOps K-UP
+syn keyword forthDefine  +FIELD BEGIN-STRUCTURE CFIELD: END-STRUCTURE FIELD:
+syn keyword forthForth   MS TIME&DATE
+
+" The optional File-Access word set {{{1
+" Handled as Core words - REFILL SOURCE-ID S\" S" (
+syn keyword forthFileMode  BIN R/O R/W W/O
+syn keyword forthFileWords CLOSE-FILE CREATE-FILE DELETE-FILE FILE-POSITION
+syn keyword forthFileWords FILE-SIZE INCLUDE-FILE INCLUDED OPEN-FILE READ-FILE
+syn keyword forthFileWords READ-LINE REPOSITION-FILE RESIZE-FILE WRITE-FILE
+syn keyword forthFileWords WRITE-LINE
+  " extension words
+syn keyword forthFileWords FILE-STATUS FLUSH-FILE RENAME-FILE REQUIRED
+syn match forthInclude '\<INCLUDE\s\+\k\+'
+syn match forthInclude '\<REQUIRE\s\+\k\+'
+
+" Non-standard File-Access words
+syn keyword forthFileWords EMIT-FILE KEY-FILE KEY?-FILE SLURP-FID SLURP-FILE
+syn keyword forthFileWords STDERR STDIN STDOUT
 syn match forthInclude '^FLOAD\s\+'
 syn match forthInclude '^NEEDS\s\+'
 
-" Locals definitions
-syn region forthLocals start='{\s' start='{$' end='\s}' end='^}'
-syn match forthLocals '{ }' " otherwise, at least two spaces between
-syn region forthDeprecated start='locals|' end='|'
+" The optional Floating-Point word set {{{1
 
-" Define the default highlighting.
+" numbers
+syn match   forthFloat      '\<[+-]\=\d\+\.\=\d*[DdEe][+-]\=\d*\>'
+
+syn keyword forthConversion >FLOAT D>F F>D
+syn keyword forthAdrArith   FALIGN FALIGNED FLOAT+ FLOATS
+syn keyword forthDefine     FCONSTANT FLITERAL FVARIABLE
+syn keyword forthFStack     FDROP FDUP FOVER FROT FSWAP
+syn keyword forthFunction   REPRESENT
+syn keyword forthMemory     F! F@
+syn keyword forthOperators  F* F+ F- F/ F0< F0= F< FLOOR FMAX FMIN FNEGATE
+syn keyword forthOperators  FROUND
+syn keyword forthSP         FDEPTH
+  " extension words
+syn keyword forthConversion F>S S>F
+syn keyword forthAdrArith   DFALIGN DFALIGNED DFLOAT+ DFLOATS SFALIGN
+syn keyword forthAdrArith   SFALIGNED SFLOAT+ SFLOATS
+syn keyword forthDefine     DFFIELD: FFIELD: FVALUE SFFIELD:
+syn keyword forthFunction   F. FE. FS. PRECISION SET-PRECISION
+syn keyword forthMemory     DF! DF@ SF! SF@
+syn keyword forthOperators  F** FABS FACOS FACOSH FALOG FASIN FASINH FATAN
+syn keyword forthOperators  FATAN2 FATANH FCOS FCOSH FEXP FEXPM1 FLN FLNP1
+syn keyword forthOperators  FLOG FSIN FSINCOS FSINH FSQRT FTAN FTANH FTRUNC F~
+
+" Non-standard Floating-Point words
+syn keyword forthOperators 1/F F2* F2/ F~ABS F~REL
+syn keyword forthFStack    FNIP FTUCK
+
+" The optional Locals word set {{{1
+syn keyword forthForth (LOCAL)
+  " extension words
+syn region forthLocals start="\<{:\>" end="\<:}\>"
+syn region forthLocals start="\<LOCALS|\>" end="\<|\>"
+
+" Non-standard Locals words
+syn region forthLocals start="\<{\>" end="\<}\>"
+
+" The optional Memory-Allocation word set {{{1
+syn keyword forthMemory ALLOCATE FREE RESIZE
+
+" The optional Programming-Tools wordset {{{1
+syn keyword forthDebug .S ? DUMP SEE WORDS
+  " extension words
+syn keyword forthAssembler ;CODE ASSEMBLER CODE END-CODE
+syn keyword forthCond      AHEAD CS-PICK CS-ROLL
+syn keyword forthDefine    NAME>COMPILE NAME>INTERPRET NAME>STRING SYNONYM
+syn keyword forthDefine    TRAVERSE-WORDLIST
+syn match   forthDefine    "\<\[DEFINED]\>"
+syn match   forthDefine    "\<\[ELSE]\>"
+syn match   forthDefine    "\<\[IF]\>"
+syn match   forthDefine    "\<\[THEN]\>"
+syn match   forthDefine    "\<\[UNDEFINED]\>"
+syn keyword forthForth     BYE FORGET
+syn keyword forthStack     N>R NR>
+syn keyword forthVocs      EDITOR
+
+" Non-standard Programming-Tools words
+syn keyword forthAssembler FLUSH-ICACHE
+syn keyword forthDebug     PRINTDEBUGDATA PRINTDEBUGLINE
+syn match   forthDebug     "\<\~\~\>"
+syn match   forthDefine    "\<\[+LOOP]\>"
+syn match   forthDefine    "\<\[?DO]\>"
+syn match   forthDefine    "\<\[AGAIN]\>"
+syn match   forthDefine    "\<\[BEGIN]\>"
+syn match   forthDefine    "\<\[DO]\>"
+syn match   forthDefine    "\<\[ENDIF]\>"
+syn match   forthDefine    "\<\[IFDEF]\>"
+syn match   forthDefine    "\<\[IFUNDEF]\>"
+syn match   forthDefine    "\<\[LOOP]\>"
+syn match   forthDefine    "\<\[NEXT]\>"
+syn match   forthDefine    "\<\[REPEAT]\>"
+syn match   forthDefine    "\<\[UNTIL]\>"
+syn match   forthDefine    "\<\[WHILE]\>"
+
+" The optional Search-Order word set {{{1
+" Handled as Core words - FIND
+syn keyword forthVocs DEFINITIONS FORTH-WORDLIST GET-CURRENT GET-ORDER
+syn keyword forthVocs SEARCH-WORDLIST SET-CURRENT SET-ORDER WORDLIST
+  " extension words
+syn keyword forthVocs ALSO FORTH ONLY ORDER PREVIOUS
+  " Forth-79, Forth-83
+syn keyword forthVocs CONTEXT CURRENT VOCABULARY
+
+" Non-standard Search-Order words
+syn keyword forthVocs #VOCS ROOT SEAL VOCS
+
+" The optional String word set {{{1
+syn keyword forthFunction -TRAILING /STRING BLANK CMOVE CMOVE> COMPARE SEARCH
+syn keyword forthFunction SLITERAL
+  " extension words
+syn keyword forthFunction REPLACES SUBSTITUTE UNESCAPE
+
+" The optional Extended-Character word set {{{1
+" Handled as Core words - [CHAR] CHAR and PARSE
+syn keyword forthAdrArith XCHAR+
+syn keyword forthCharOps  X-SIZE XC-SIZE XEMIT XKEY XKEY?
+syn keyword forthDefine   XC,
+syn keyword forthMemory   XC!+ XC!+? XC@+
+  " extension words
+syn keyword forthAdrArith   XCHAR- +X/STRING X\\STRING-
+syn keyword forthCharOps    EKEY>XCHAR X-WIDTH XC-WIDTH
+syn keyword forthConversion XHOLD
+syn keyword forthString     -TRAILING-GARBAGE
+
+" Define the default highlighting {{{1
+hi def link forthBoolean Boolean
+hi def link forthCharacter Character
 hi def link forthTodo Todo
 hi def link forthOperators Operator
 hi def link forthMath Number
@@ -243,6 +430,7 @@
 hi def link forthConversion String
 hi def link forthForth Statement
 hi def link forthVocs Statement
+hi def link forthEscape Special
 hi def link forthString String
 hi def link forthComment Comment
 hi def link forthClassDef Define
@@ -251,16 +439,17 @@
 hi def link forthEndOfObjectDef Define
 hi def link forthInclude Include
 hi def link forthLocals Type " nothing else uses type and locals must stand out
-hi def link forthDeprecated Error " if you must, change to Type
 hi def link forthFileMode Function
 hi def link forthFunction Function
 hi def link forthFileWords Statement
 hi def link forthBlocks Statement
 hi def link forthSpaceError Error
+"}}}
 
 let b:current_syntax = "forth"
 
 let &cpo = s:cpo_save
 unlet s:cpo_save
-" vim:ts=8:sw=4:nocindent:smartindent:
+
+" vim:ts=8:sw=4:nocindent:smartindent:fdm=marker:tw=78